A wrong-way driver whose vehicle smashed into an off-duty cop's car Monday killed both himself and the officer after driving some 35 miles in the opposite direction down an Arizona freeway.

The 911 calls began coming in around 12:30 a.m. as the wrong-way driver's SUV headed down a freeway in far north Phoenix, The Associated Press reported. Highway patrol officers with the Arizona Department of Public Safety rushed to intercept the driver as he continued west in the eastbound lanes of the Loop 101 freeway.

Authorities fielded more calls as the driver jumped onto another freeway, still headed in the wrong direction.

An officer had slowed traffic and tried to ram the SUV to stop it as it drove through Phoenix, but the driver swerved and continued on.

Within a half-hour of triggering the first 911 calls, the wrong-way driver collided with Brandon Mendoza's car on a ramp connecting Intestate 10 and the U.S. 60 freeway.

Authorities are awaiting autopsy results to identify the wrong-way driver and the level of drugs or alcohol, if any, that were in his body at the time of the crash, Department of Public Safety spokesman Officer Carrick Cook said.

Mendoza, 32, was approachable, empathetic and dedicated to his community, working to rehabilitate a park as a community gathering spot, Mesa Police Chief Frank Milstead said.

"Brandon would not be stopped," Milstead said of the park project. "He was everything that a police chief would want an officer to be."

Both Milstead and Cook said Mendoza, who was driving home in his personal car, likely only had seconds of warning before the crash.

"My guess is he was absolutely caught off-guard . . . because it is a blind curve and they were coming from different directions at freeway speed," Milstead said.

Cook said at least a half-dozen Department of Public Safety officers were involving in trying to stop the wrong-way driver.

"We were scrambling," Cook said. "Nobody was really pursuing. We were just trying to intercept."